Dietary fat intake reduction is a conceptually new approach to adjuvant breast cancer management. The rationale supporting evaluation of dietary fat intake reduction in management of patients with localized breast cancer is based on: epidemiologic observations of major differences in stage-by-stage survival of patients comparing outcome in countries with low (JAPAN) vs high (Western) diet- ary intakes; relationships between dietary fat intake and factors prognostic of clinical outcomes; adverse effects of weight gain.